JP5906200B2 - Automatic placement of imaging planes in ultrasound imaging - Google Patents

Description

  The present invention relates to a method for ultrasound imaging using at least two two-dimensional images intersecting each other, an ultrasound imaging device configured to carry out such a method, a system comprising such an ultrasound imaging device, and such a method. The present invention relates to a computer program to be executed, and a computer-readable medium storing such a computer program.

  Real-time ultrasound is routinely used to guide interventional procedures such as biopsy and local ablation therapy (including radio frequency ablation). With the recent introduction of real-time multiplanar reconstruction (MPR) and bi-plane ultrasound in mechanical and matrix transducers, it is now possible to collect real-time anatomy information in any plane. In biplane ultrasound imaging, two imaging planes are generated. Both planes intersect the transducer active aperture. MPR is a method for reconstructing a two-dimensional image from a set of raw image data. That is, any image with a different direction can be calculated from the set of cross-sectional images. For example, it is a front, sagittal or inclined cross-sectional image. In MPR, the imaging plane so determined that does not intersect the transducer aperture is called the C plane.

  US2007 / 0073155A1 describes a compact ultrasonic needle guidance system and method that determines the needle destination in the imaging plane of a two-dimensional ultrasonic image to be adjustable before inserting the needle into a patient. In this system, a needle holder is provided for an ultrasound probe that acquires a two-dimensional image of a subject to be examined. Assuming that the direction of the needle does not change during insertion, knowing the position of the needle holder and thus the direction of the needle, the intersection point of the two-dimensional image and the needle can be determined. This intersection point can be marked when displaying a two-dimensional image on the display. However, this system is not very flexible in use. As a result, there is a need for alternative imaging methods and systems.

  An object of the present invention is to provide an alternative method and system for ultrasound imaging.

  The object is solved using the method and system described in the independent claims. Further advantageous developments are described in the dependent claims.

  According to an embodiment of the invention, a method for ultrasound imaging is provided. There, an object to be examined, for example an interventional object that is moved to a target area included in a patient, is acquired, preferably a first two-dimensional image aligned with the longitudinal direction of the needle. This alignment means that the longitudinal axis of the interventional object is substantially or exactly included in the imaging plane of the first image. Furthermore, the position and orientation of the interventional object is automatically determined before or after the first two-dimensional image is acquired. This order depends on how the position and direction are determined. Preferably, this can be performed using image feature analysis, or by electromagnetically tracking an interventional object, or by position determination with an optical sensor. When using image feature analysis, or when determined by an optical sensor, the position of the interventional object can be determined prior to acquiring any image. When using image feature analysis, at least one image must be acquired as the basis for determining the location of the interventional object. Based on the position and direction of the interventional object, the position of the second two-dimensional image is automatically determined, and the second two-dimensional image is acquired. The second two-dimensional image intersects the longitudinal direction of the interventional object, and preferably the imaging planes of the first and second images are perpendicular to each other. When MPR is used, the C-plane is selected so that it is also perpendicular to the longitudinal axis of the interventional object. The term “acquire” can include acquiring images using a transducer and data processor in the case of biplane ultrasound, and in the case of MPR, acquiring the desired image from an available database. Can be included. Similarly, the term “acquisition device” can include not only transducers, but also modules of a computer or data processor that acquire a desired image from an available database.

  This embodiment allows the movement of a moving interventional object to be automatically tracked. As a result, a desired image of the object under inspection can be displayed. Here, this imaging is fixed with respect to interventional object movement. Thus, the processing of the imaging system requires fewer participants and the user, for example a surgeon, can concentrate more on other tasks. Ultrasound is advantageous over computed tomography (CT) in that it provides a true real-time imaging modality for guidance. This provides more confidence to the interventional radiologist when guiding the needle against the target area.

  According to a further embodiment, a method is provided, wherein the step of determining the position and orientation of the interventional object determines the position of the interventional object tip, in particular the needle tip. The position of the second image is determined such that the second image is moved a predetermined distance forward of the tip.

  In this regard, the inventors of the present invention have found that when using conventional methods and systems, the user does not get a good overview of which barriers the interventional object encounters along its trajectory. Noticed. Thus, a “virtual endoscope” is provided for the ultrasound imaging device. Preferably, the method includes adjusting the C-plane (when MPR is used) or the transverse plane (when using bi-plane ultrasound) so that the plane is always slightly forward of the needle tip. When using MPR, the needle shaft is preferably always perpendicular to the C-plane. This imaging plane configuration particularly provides the user with information regarding the immediate scenery in front of the needle tip. This allows the user to anticipate and adjust the needle trajectory as needed, for example to avoid hitting the main blood vessel.

  According to yet another embodiment, the position and direction of the interventional object is iteratively determined, and the position of the second image is determined by the changing position and / or direction of the interventional object. Is adapted to. Thus, the position of the interventional object and the execution of the adjustment are periodically tracked so that the distance remains constant while the interventional object is moved. Thus, the user gets an update of the landscape information while the interventional object is inserted. This update can be performed in real time within a predetermined time interval.

  According to a further embodiment, the method is completely automatic. On the other hand, in another embodiment, the method interacts with the user, for example by requesting the input of the desired distance.

  According to yet another embodiment, the method includes obtaining and displaying a plurality of transverse planes that are located at different distances in front of the needle tip. The user can get an additional overview of what is in the path before the needle when keeping the needle in the current direction.

  Furthermore, the present invention provides an ultrasound imaging device configured to perform at least one of the above methods, a computer program for performing such a method, and a computer readable medium storing such a computer program. All these provide the same advantages as the embodiments described above.

  The gist of the present invention can be seen as providing a method by which ultrasound signals are acquired that allow the display of at least two imaging planes including the region of interest. One of these imaging planes is aligned with the main axis of the needle, and the other plane is transverse to it and positioned at a predetermined distance in front of the needle tip.

It is a figure which shows an imaging system roughly using the three-dimensional illustration of two imaging planes. 1b is a top view of the imaging plane of FIG. 3 is a flowchart illustrating a method for ultrasound imaging according to an embodiment of the present invention.

  These and other aspects of the invention will be apparent from and will be elucidated with reference to the embodiments described hereinafter.

  FIG. 1a schematically illustrates an imaging system 1 according to an embodiment of the invention. FIG. 1a further shows two imaging planes in a three-dimensional display, and FIG. 1b shows a top view projection of these imaging planes along the plane containing the longitudinal axis of the needle as seen from the active aperture of the transducer. 1a and 1b exemplarily illustrate the case of biplane ultrasound imaging. However, the teachings of the present invention are equally applicable in multiplanar reconstruction (MPR). In MPR and biplane ultrasound imaging, it is possible to display at least two vertical imaging planes simultaneously. One plane is along the main axis of the interventional device, for example a medical needle, and another plane is perpendicular to the main axis of the interventional device in the top view of FIG. 1b. Such an arrangement is beneficial when guiding the interventional device to the target lesion under real-time ultrasound guidance.

  FIG. 1 a shows a transducer 2 that transmits and receives ultrasound signals contained in a first imaging plane 8, for example an azimuthal plane. Furthermore, a transducer 2 is provided for transmitting and receiving ultrasonic signals contained in the second imaging plane 9. For example, in the case of biplane ultrasound, a transverse plane or biplane is used, and in the case of MPR, the C plane is used. The transducer 2 is preferably a 2D array matrix transducer. Such 2D array matrix transducers have an array of transducer elements configured, for example, in a chessboard or segmented ring-like manner on the surface facing the object to be examined. Each of these transducer elements has its own transmit / receive channel. In this way, individual transducer elements can be controlled individually. By driving them appropriately, the resulting ultrasound beam is tilted, rotated (around the axis along the vertical axis or the center beam of the transducer), and physically transducers like previous devices. Can be focused electronically without the need for rotational rotation. The transducer 2 is connected to a data processor 4 that is configured to control the transducer 2. Furthermore, the data processor 4 reconstructs the two-dimensional images 10 and 11 included in the imaging planes 8 and 9, respectively, corresponding to the ultrasonic signals acquired by the transducer 2. Images 10 and 11 provide a reconstruction of an object to be examined, for example a patient (not shown). A specific target area 7 of the object, for example a target lesion, is intersected by at least a first imaging plane 8. These images 10 and 11 can be displayed on a display 5 connected to the data processor 4. The imaging system 1 also has a user interface 6 provided to the user for operating the imaging system 1.

  FIG. 1 a further shows the needle 13. The needle can also be any other interventional device. The first imaging plane 8 is arranged so as to be aligned with the longitudinal axis 14 of the needle 13. That is, this longitudinal axis is included in the first imaging plane 8. For example, by applying image feature analysis, such as a shape recognition algorithm known in the prior art, to at least the first image 10, the position and direction of the needle 13, particularly the shaft direction and the position of the needle tip 15, are automatically displayed in the image 10. Can be recognized. For this purpose, the data processor 4 can perform a feature analysis method and can therefore function as a detection device.

  In an alternative embodiment, the position and orientation of the needle 13, particularly the shaft direction and the position of the needle tip 15, is automatically performed by electromagnetic tracking, such as the electromagnetic needle tip tracking introduced by Traxtal, Inc. that implements an automatic tip tracking function. Be recognized. For this purpose, a separate electromagnetic tracking device must be provided, as is known from the prior art. These devices are connected to the data processor 4.

  This information is used in real time to determine the position and / or orientation of the second imaging plane 9. As a result, this plane is slightly forward of the needle tip 15 by a distance of 16 minutes, which is the distance along the longitudinal axis 14 between the needle tip 15 and the point where the longitudinal axis 14 intersects the second imaging plane 9. It is advanced. In FIG. 1b, a projection of a distance 16 on the top view is shown. In this case, such a projection can also be used as an associated distance. This distance 16 can be set by controlling individual transducer elements of the transducer 2. As a result, the resulting ultrasound beam is rotated about an axis along the vertical axis or the central beam of the transducer, and a tilting action is realized as indicated by the arrow marked with reference numeral 17. So that it is tilted about the axis 12. Reference numeral 18 indicates an intersection line between the first and second imaging planes. When using MPR, the second imaging plane 9 can additionally be chosen to be perpendicular to the longitudinal axis 14. The preferred distance between the needle tip 15 and the second imaging plane 9 should be such that it gives the user sufficient time to make adjustments to the needle trajectory as needed. A preferred distance is anywhere between a few millimeters to a few centimeters. This distance is more preferably in the range of 1-5 mm and is determined automatically and iteratively by the imaging system, or is determined automatically once and kept constant during the imaging procedure, or the user interface 6 Is either determined by the user using. If this distance is determined automatically, it can be determined based on the type of interventional object, the speed of movement of the interventional object, the type of object to be examined and / or the target area. . In this context, the embodiment has an innovative interface to the user or operator to identify the distance between the second imaging plane 9 and the needle tip 15. For example, the user can be prompted to enter a desired distance in centimeters or millimeters. When this distance is input, the imaging system is activated to acquire and display the second imaging plane 9 in front of the needle tip 15 by a desired distance.

  By having the position and / or direction of the needle 13, the point where the longitudinal axis 16 intersects the second imaging plane 9 is marked in the acquired second image 11 when displayed on the display 5. Can do. In use, the imaging planes 8 and 9 will follow the movement of the needle to achieve a raw ultrasound image. The marker is superimposed on the raw ultrasound image, for example by a crosshair or by a circle surrounding the intersection point. In this way, the expected path of the needle can be displayed.

  In the present embodiment, information regarding the needle tip 15 and shaft direction drives the transducer 2 (ultrasound scanner or beamformer) in real time and how the second imaging plane 9 (cross section) is created. To decide. When the ultrasound imaging system 1 operates in MPR mode (which can be 4-dimensional or C-plane mode), the transducer need not be position / orientated. This is because all the imaging planes are collected. In this case, the adjustment is applied to the MPR image reconstruction step. This can be done on the ultrasound system imaging system or on an external computer.

  The scouring with respect to the above is performed in order to return the plane to the needle tip 15 or to change the plane from the needle tip 15 so that the trajectory of the needle can be predicted with respect to the object to be examined, for example, the surrounding anatomy. To move away, the user or operator can quickly slide the second imaging plane 9 along the needle shaft.

  FIG. 2 is a flow chart illustrating the above described method for automatic positioning of the second imaging plane 9 with reference to the indicated method steps. This figure shows a case where the position and direction of the needle 13 are determined using image feature analysis when biplane imaging is performed. In the first step S <b> 100, the user aligns the first imaging plane 8 along the shaft of the needle 13. For this purpose, the first image 10 is displayed on the display 5. This first imaging plane 8 also shows the needle tip 15. As a result, in the next step S101, the position and direction of the needle 13 are determined by applying image feature analysis. When an additional image that is initially perpendicular to the first image 8 (and perpendicular to the needle shaft in the top view seen from the active aperture of the transducer) is placed on the needle tip 15 by the user, the more accurate position and Direction data can be realized. Alternatively, for the alignment of the first imaging plane 8 by the user, this alignment acquires the image, analyzes the image by a feature analysis method for the presence, position and orientation of the needle, and the first imaging plane 8 Can be realized automatically by updating the position and repeating this until the needle 13 is accurately aligned with the longitudinal axis 14.

  Based on the determined position and direction of the needle 13, and in particular based on the shaft direction and the position of the needle tip 15, the position of the second imaging plane 9 is automatically determined in step S102. Based on this information, the second transducer 3 can be arranged as described above (eg tilted). In step S103, an image included in the second imaging plane 9 can be acquired. This image shows the expected path of the needle 13, that is, an image ahead of the needle tip 15 by a predetermined distance. In step S104, the second image 9 is displayed on the display 5. In this case, the intersection between the longitudinal direction of the interventional object and the second image is marked. At least steps S101 to S104 are performed iteratively to track the movement of the needle 13 and adapt the position of the second imaging plane 9 accordingly. Also, the first step S100 changes the direction of the needle every few hours or every time to ensure that the first image 10 is kept aligned with the first imaging plane 10. Can be included in an iterative loop.

  When using electromagnetic tracking of the needle 13, the execution order of steps S100 and S101 is exchanged. In this case, the position and direction of the needle 13 is determined first. Based on this information, the first and second images 10 and 11 can be acquired substantially simultaneously. Here, the first image is aligned with the needle 13, and the second image 11 is moved away by a predetermined distance in front of the needle tip 15.

  According to a variation of this embodiment, and preferably in connection with MPR imaging, a plurality of C's are provided to provide the user with more information regarding what the needle encounters should keep its trajectory the same. A plane is displayed at the same time. For example, each C-plane can be perpendicular to the needle shaft and is located at a given distance in front of the needle tip 15. For example, the first C plane is disposed 2 mm forward of the needle tip 15, the second C plane is disposed 5 mm forward of the needle tip, and the third C plane is the front of the needle tip 15. It is arranged at a place of 20 mm. The additional information provided to the user regarding the structure of the object under examination that is in front of the needle tip 15 is further useful for initially correcting the needle trajectory, for example to avoid hitting the main blood vessel. This can also be realized using biplane ultrasound imaging. In this case, multiple transverse planes are provided instead of the C plane.

  These multiple images in front of the needle tip 15 can be displayed on the display 5. In this case, markers such as crosshairs or circles, for example, indicate the intersection of the individual indication intersecting with the longitudinal axis of the needle 15 and the longitudinal axis of the needle 15, respectively. In this connection, the longitudinal axis of the needle or the trajectory of the projected needle tip can be displayed on multiple C planes as a red dot or red circle. This point or circle becomes smaller as the needle tip 15 actually approaches a given C plane.

  These multiple images in front of the needle tip 15 can be integrated into a video sequence. In this way, the surgeon can interrupt the interventional procedure and play a video sequence of images in front of the needle tip 15. In this way, the operator can record the sequence of the C plane arranged in front of the needle tip 15 and reproduce the sequence to plan the needle trajectory. In other words, the size and / or display of the marker may depend on the distance 16. If the acquisition of the C plane is repeated every few seconds (eg every 3 seconds) when moving the needle, the marker circle will continually become smaller and suddenly larger when the acquisition is repeated.

  Advantageously, an innovative user interface 6 can be provided. Using this interface, the user can see on the display 5 the distance 16 between the second imaging plane 9 and the needle tip 15, the number of transverse planes / C planes displayed on the display 5 (second plane + needle). The total number of additional surfaces intersecting the 13 longitudinal directions) and the position of the transverse plane / C plane relative to the needle tip 15 can be entered.

  The above embodiments have been described with reference to 2D array matrix transducers. However, the present invention can also be realized by using mechanical transducers in which an array of piezoelectric elements is mechanically scanned back and forth across the volume of interest. Also, separate transducers for each imaging plane are possible.

  The teachings of the present invention are specifically intended to cover any combination of the above-described embodiments or variations.

  While the invention has been illustrated and described in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention has been disclosed. It is not intended to be limited to the embodiments. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims (12)

In a method relating to ultrasonic imaging,
Obtaining a first two-dimensional image disposed along and including the longitudinal direction of an interventional object that is moved to a target region included in the object to be examined;
Obtaining a second two-dimensional image intersecting the longitudinal direction of the interventional object, wherein a position of the second two-dimensional image is automatically determined of the interventional object. Automatically determined based on the position and direction of
Determining the position and orientation of the interventional object comprises determining a position of a tip of the interventional object;
A position of the acquired second two-dimensional image is determined at a predetermined distance from the determined tip position ;
The method wherein the distance is automatically determined based on the type of interventional object, the speed of movement of the interventional object, the type of object to be examined and / or the type of the target area .   The position and direction of the interventional object is iteratively determined and the position of the second two-dimensional image is adapted to the changing position and / or direction of the interventional object, The method of claim 1. Obtaining at least one further two-dimensional image intersecting the longitudinal direction of the interventional object;
The method according to claim 1 or 2, wherein the at least one additional image is arranged at a predetermined distance from the second two-dimensional image.   The method of claim 1, wherein the position and orientation of the interventional object is determined by image feature analysis.   The method of claim 1, wherein the position and orientation of the interventional object is determined by electromagnetic tracking of the interventional object.   The method of claim 1, wherein the distance is adjustable by a user. A first two-dimensional image aligned with the longitudinal direction of the interventional object to be moved to the target area included in the object to be examined is displayed on the display screen,
The method of claim 1, wherein the second two-dimensional image intersecting a longitudinal direction of the interventional object is displayed on the display screen. The method of claim 7 , wherein an intersection between a longitudinal direction of the interventional object and the second two-dimensional image is marked in the displayed image. An ultrasound imaging device,
An acquisition device for acquiring first and second two-dimensional images;
A detection device for determining the position and direction of an interventional object that is moved to a target area included in the object to be examined,
The first two-dimensional image is disposed along a longitudinal direction of the interventional object and includes the longitudinal direction;
The second two-dimensional image intersects the longitudinal direction of the interventional object;
The acquisition device is configured to acquire the second two-dimensional image at a position based on the position and orientation of the interventional object;
The detection device is configured to determine a position of a tip of the interventional object;
The acquisition device acquires the second two-dimensional image at a predetermined distance forward from the determined tip position, and the distance is determined by the interventional object type, the interventional An ultrasound imaging device , automatically determined based on a moving speed of an object, the object to be examined and / or the type of the target area . A system comprising the ultrasound imaging device of claim 9 and an interventional object.   The computer program for making a computer perform each step of the method of Claim 1.   A computer readable medium storing the computer program according to claim 11.

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